Water makes up around 70% of the Earth’s surface, but just 3% of that water is fresh. Much of this freshwater is frozen in glaciers, and some of it may be found In rivers and lakes, but 30% of it is groundwater, but what exactly is groundwater?
Groundwater is water that seeps through cracks in the rocks and sediments beneath the surface. Water may find its way into an aquifer as it seeps into the ground. Aquifers are groundwater-saturated subsurface rock layers. An aquifer is a huge permeable layer of rock, not an underground river.
The Floridan aquifer, for example, spans approximately 100,00 square miles and includes the entire state of Florida. Consider an aquifer to be a massive underground sponge that soaks up water that falls to the earth’s surface.
You might hit water if you grab the shovel and start digging below. The water table is the first body of water you come upon. The mark may be fully submerged below the water table. The saturated zone is what it’s called. The rocks and minerals above the saturation zone, known as the unsaturated zone, may be dry, so how can this water accumulate in the ground?
When it rains, part of the water seeps into the earth, where it can stay for thousands of years if it travels deep enough. However, not all of the groundwater is underground, and much of the surface water is derived from groundwater and aquifers.
When the ground sinks below the water table, the groundwater will rise to the surface, perhaps forming a lake. A stream can be formed by groundwater flowing out. Although this is referred to as a spring, some groundwater is difficult to get. Contained aquifers are these underground water bodies. Humans rely on groundwater for drinking and agricultural purposes.
Nonetheless, contaminated groundwater poses a severe hazard, particularly in urban areas. The management of the resource is frequently complex and difficult due to many contaminants and sources.
New pollutants (emerging contaminants) have been discovered as a result of industrialization and urbanization, and municipal wastewater treatments systems must be regularly updated to remove the pollutants before the treated wastewater is discharged into surface water bodies. Contamination can make groundwater unfit for human consumption. Contamination of groundwater is extremely difficult, if not impossible, to remove.
What is Groundwater Contamination?
When pollutants are released into the earth and find their way into groundwater, this is known as groundwater contamination. This form of water pollution can also occur naturally as a result of the existence of a minor and undesired element, contaminant, or impurity in the groundwater, in which case it is referred to as contamination rather than pollution.
Groundwater contamination happens when man-made items such as gasoline, oil, road salts, and chemicals contaminate the water, rendering it hazardous for human consumption. On-site sanitation systems, landfill leachate, effluent from wastewater treatment facilities, leaking sewers, petrol filling stations, hydraulic fracturing (fracking), and overuse of fertilizers in agriculture can all pollute groundwater.
Materials from the surface of the land can pass through the soil and into the groundwater. Pesticides and fertilizers, for example, can make their way into groundwater supplies over time. Groundwater may also be contaminated by road salt, hazardous compounds from mining sites, and wasted motor oil.
Untreated sewage from septic tanks, as well as harmful chemicals from underground storage tanks and leaking landfills, can contaminate groundwater.
Naturally occurring pollutants like arsenic or fluoride can also cause pollution (or contamination). Using contaminated groundwater endangers public health by causing poisoning or the spread of disease (water-borne diseases).
Causes of Groundwater Contamination
For water to be polluted, there need to be just a little alteration to its quality and so the causes of groundwater contamination are numerous and it cut across the various aspect of our daily living so, you might need to ask yourself if you are contributing to groundwater contamination through your daily activities. The following are the causes of groundwater contamination.
- Naturally Occurring(Geogenic) Chemicals
- Storage Tanks
- Petroleum Products
- Septic Systems
- Uncontrolled Hazardous Waste
- Chemicals and Road Salts
- Atmospheric Contaminants
- Improper Sewage Disposal
- Excessive Use of Fertilizers and Pesticides
- Agricultural Chemicals
- Industrial Pipe Leakage and Other Industrial Releases
- Overpumping of Groundwater
- Surface Impoundments
1. Naturally Occurring(Geogenic) Chemicals
Naturally occurring chemicals are one of the causes of groundwater contamination. Contamination can occur when naturally existing chemicals in soils and rocks dissolve in water. Sulfates, iron, radionuclides, fluorides, manganese, chlorides, and arsenic are among these compounds. Others, such as rotting soil components, may seep into underground water and move as particles with it.
Fluoride and arsenic are the most common contaminants, according to WHO reports. The Groundwater Assessment Platform can be used to investigate the natural causes of pollution (GAP). GAP uses environmental, geological, and topographical data to calculate pollution levels.
Arsenic is a naturally occurring element that can be found in the crust of the planet. It is toxic and quite fatal in its natural state. It dissolves in groundwater as a result of anaerobic conditions created by organic matter within aquifers.
Iron oxides are discharged into groundwater aquifers as a result of microbial degradation of organic materials. These iron oxides react with the arsenic to form arsenic compounds such as arsenite and arsenate, with the former being more dangerous than the latter.
The second main source of geogenic groundwater contamination is fluoride compounds present in groundwater. These are found in aquifers that are deficient in calcium. Since 1984, the WHO has set an acceptable limit of 1.5 mg/l for fluoride concentration in groundwater. More than this can lead to “dental fluorosis,” a disorder defined by tooth enamel hypomineralization.
2. Storage Tanks
Storage tanks are one of the causes of groundwater contamination. They can be above or below ground and can contain gasoline, oil, chemicals, or other forms of liquids. Over 10 million storage tanks are projected to be buried in the United States, and these tanks can corrode, crack, and leak over time. There is a risk of serious pollution if the toxins break out and enter the groundwater.
3. Petroleum Products
Petroleum products are one of the causes of groundwater contamination. There are two types of petroleum storage tanks: underground and above ground. Furthermore, petroleum products are primarily transported underground through pipelines. Water pollution can occur as a result of leakages from these substances.
Chemical spills from trucks, storage containers, and trains are projected to cause 16,000 chemical accidents in the United States each year, particularly while transporting oil. The spilt chemicals are diluted by water and seep into the ground, potentially contaminating groundwater.
4. Septic Systems
Septic systems are one of the causes of groundwater contamination. Homes, workplaces, and other structures that are not connected to a public sewer system employ onsite wastewater disposal systems. Septic systems are designed to progressively drain human waste underground in a safe and environmentally friendly manner. A septic system that is incorrectly built, situated, constructed, or maintained can cause major difficulties by leaking nitrates, oils, detergents, bacteria, viruses, household chemicals, and other toxins into the groundwater.
Septic systems are the leading source of groundwater contamination all over the world. Poop, septic tanks, and cesspools all contribute to the pollution. Because so many people rely on the septic system, it is one of the most polluting systems.
Because they produce organic compounds like trichloroethane, commercial septic tanks are considerably more dangerous. Most nations have laws requiring septic tanks to be built far away from water sources to prevent contamination, but this is not always the case.
5. Uncontrolled Hazardous Waste
Uncontrolled hazards are one of the causes of groundwater contamination. There are about 20,000 known abandoned and uncontrolled hazardous waste sites in the United States today, and the number is growing every year. If barrels or other containers are hanging about that are full of dangerous materials, hazardous waste sites can lead to groundwater contamination. These toxins can eventually make their way down through the soil and into the groundwater if there is a leak.
Landfills are one of the causes of groundwater contamination. They are the locations where our trash is taken to be buried. To prevent toxins from entering the water, landfills are meant to have a protective bottom layer. Contaminants from the waste (vehicle battery acid, paint, etc.) can make their way down into the groundwater if there is no layer or if it is fractured.
The Love Canal, an abandoned canal project in Niagara Falls, New York, is one of the most prominent examples of groundwater pollution caused by landfill leachate. In 1978, the area began reporting a high incidence of cancer and birth defect cases among the local people. The examination revealed that it was caused by organic/inorganic hazardous pollutants leaking into the groundwater from the nearby industrial dump.
7. Chemicals and Road Salts
Another cause of groundwater contamination is the widespread use of pesticides and road salts. Chemicals include weed killers, insecticides, and fertilizers used on lawns and farm fields, as well as items utilized in homes and businesses. These chemicals can seep into the ground and eventually into the water when it rains. In the winter, road salts are used to melt ice on roadways so that cars do not slide around. When the ice melts, the salt is swept away from the roadways and into the river.
8. Atmospheric Contaminants
Atmospheric contaminants are one of the causes of groundwater contamination. Because groundwater is a component of the hydrologic cycle, contaminants from other sections of the cycle, such as the atmosphere or bodies of surface water, can eventually find their way into our drinking water.
9. Improper Sewage Disposal
When sewage is not disposed of properly, they don’t just affect the land and nearby water bodies, they cause groundwater contamination. This issue emerges in locations with a lack of sewage treatment plant infrastructure or poorly maintained sewer systems.
Furthermore, if micro-pathogens such as hormones, pharmaceutical residues, and other micro-contaminants found in urine or faeces are present in the sewage, even conventional treatment plants may be unable to eliminate them. Pharmaceutical residues on the order of 5-ng/L were discovered in groundwater in many places across Germany.
10. Excessive Use of Fertilizers and Pesticides
Pesticides and commercial fertilizers, as well as natural fertilizers such as manure, are nitrogen-based substances that cause groundwater contamination by introducing nitrates. This is since plants only use a small percentage of nitrogen, leaving the rest to be washed into water bodies or seeped into the ground, poisoning aquifers. In addition, if the animals were given veterinary treatments, animal excrement may contain pharmaceutical contaminants.
11. Agricultural Chemicals
To improve crop output, millions of tons of agricultural chemicals such as fertilizers and insecticides are utilized around the world. These chemicals are also used by other organizations, such as golf courses.
Excessive usage of these substances can lead to groundwater contamination. Pesticides, for example, have been known to stay in the ground for years and, when diluted by rains, seep further into the groundwater.
12. Industrial Pipe Leakage and Other Industrial Releases
Groundwater contamination around industrial regions is often caused by leakage from subterranean industrial pipes and oil tanks. Because of inappropriate waste management, hazardous metals such as arsenic may be introduced into the groundwater during ore and metal mining.
Other dangerous metals might easily dissolve in their waste and infiltrate into the aquifers due to their acidic nature. Similarly, if gasoline stations’ storage tanks burst and discharge benzene and other low-density substances into the earth, they may pollute groundwater. Due to their lower densities than water, these chemicals will float on the upper surface of the water table, rendering them inappropriate for domestic usage.
13. Overpumping of Groundwater
Overpumping of groundwater is one of the causes of groundwater contamination. Pumping groundwater at a high rate can lead to the discharge of arsenic into the water, as well as soil subsidence (sudden sinking of land). Arsenic is mostly found in the clayey layer of the subterranean surface, and only a small amount of it escapes into the water during pumping. However, due to the huge hydraulic gradient caused, a significant amount may enter aquifers if overdone.
14. Surface Impoundments
Surface impoundments are one of the causes of groundwater contamination. These are shallow lagoons where liquid waste is stored. In the United States, for example, there are approximately 180,000 surface impoundments that can pollute groundwater. As a result, clay liners or leachates are required in the impoundments to avoid leaching. In some situations, the leachates may be faulty, resulting in leaks and water contamination.
Effects of Groundwater Contamination
Groundwater contamination poses a threat to all living beings. It doesn’t just affect humans or plants; it affects everyone. As a result, below are some of the consequences of groundwater contamination.
- Health Issues
- Affects Economic Growth
- Damage to Aquatic Systems and the Overall Ecosystem
- Lack of Enough Drinking Water
- Lack of Clean Water for Industries
1. Health Issues
Groundwater contamination is hazardous to one’s health. Human excrement may contaminate water sources in situations where septic tanks are not installed correctly. Poisoning from excessive pesticides and fertilizers, as well as natural chemicals, might cause additional health concerns. The chemicals contaminate water sources by leaching into them. Drinking water from such a source could be harmful to your health.
- Waterborne Diseases
- Dental Fluorosis
When groundwater contamination occurs, it can cause waterborne infections. It can induce dysentery, which can result in severe diarrhoea, dehydration, and death in some cases. For example, the World Health Organization discovered that the groundwater in Bangladesh is polluted, resulting in an annual increase in waterborne infections. As a result, groundwater pollution may cause waterborne infections in humans, as well as mortality.
This is a dental condition in which the teeth turn brown. This is mainly due to high fluoride levels in the water. Fluoride levels in groundwater are high due to a lack of calcium in the water. This is one of the consequences of groundwater contamination.
The lack of well-built sewerage systems may cause contamination of groundwater, resulting in Hepatitis and irreparable liver damage. This is because human waste comes from groundwater contamination. So, while drilling your well, make sure it’s in the right place to avoid such problems.
2. Affects Economic Growth
Groundwater contamination supplies make the area unfit for plant, human, and animal life to thrive. The population of the area decreases, and the value of the land decreases. Another effect is that industries that rely on groundwater for production suffer from reduced stability. No one can leave or acquire land without access to safe drinking and cooking water.
As a result, if your land is located in an area where groundwater pollution is at its worst, its value will plummet. This is because plants, animals, and people are unable to thrive in this environment. As a result, enterprises in the impacted areas may have to rely on water from other regions, which could be costly. Furthermore, due to low water quality, they may be compelled to close.
3. Damage to Aquatic Systems and the Overall Ecosystem
Groundwater contamination has the potential to wreak havoc on the ecosystem. One such change is the loss of specific nutrients that are necessary for the ecosystem’s self-sustenance. Additionally, when contaminants interact with water bodies, the aquatic ecosystem may be altered. As a result of too many toxins in the water bodies, aquatic species such as fish may die off quickly.
Animals and plants that drink contaminated water may be harmed as well. Toxic compounds build up in aquifers over time, and once the contamination spreads, the groundwater may become unfit for human and animal consumption. The consequences are severe, particularly for those who rely on groundwater during droughts.
4. Lack of Enough Drinking Water
Many countries are having trouble finding clean drinking water as a result of groundwater contamination. These effects are adverse because people are not able to drink clean water which leads to health complications. To learn more about the lack of drinking water, we have just made an article on drought just for you.
5. Lack of Clean Water for Industries
The majority of industries discharge effluents that cause groundwater contamination. Finally, some of these businesses are affected by a shortage of clean water. There can be no production without clean water. As a result, industries will close and jobs will be lost.
Prevention of Groundwater Contamination
Contaminated groundwater can remain for years, making cleanup difficult and costly. The answer to avoiding pollution is to prevent it. The following ways are the prevention of groundwater contamination.
- Go Native
- Reduce Chemical Use
- Waste Management
- Don’t Let It Run
- Fix the Drip
- Wash Wisely
- Use Water Efficiently
- Reduce, reuse, and recycle
- Natural Substitutes
- Learn and do more!
1. Go Native
Plants that are natural to your area should be used in your landscaping. They have a fantastic appearance and don’t require much water or fertilizer. Choose grass varieties that are suitable to your region’s environment, since this will reduce the need for frequent watering and chemical applications.
2. Reduce Chemical Use
Reduce the number of chemicals you use in your house and yard, and make sure they’re properly disposed of.
Dispose of potentially harmful materials such as unused chemicals, medications, paint, motor oil, and other materials properly. Household hazardous waste collections or disposal sites are held in several localities.
4. Don’t Let It Run
When brushing your teeth or shaving, turn off the water and don’t leave it running while waiting for it to cool down. Instead, keep a pitcher of cold water in the fridge.
5. Fix the Drip
Check for leaks in all of your home’s faucets, fixtures, toilets, and taps and replace them right away, or install water-saving models.
6. Wash Wisely
Limit yourself to a five-minute shower and dare your family to follow suit! Also, only run full loads of dishes and laundry in the dishwasher and washer.
7. Use Water Efficiently
Water the lawn and plants only when they are thirsty and during the coldest portions of the day. During dry periods, make sure you, your family, and your neighbours follow any watering restrictions.
8. Reduce, reuse, and recycle
Reduce, reuse and recycle is an efficient method of preventing groundwater contamination. Reduce the quantity of “things” you use and recycle as much as possible. Paper, plastic, cardboard, glass, aluminium, and other materials can all be recycled.
9. Natural Substitutes
When feasible, use only natural/nontoxic household cleaners. Lemon juice, baking soda, and vinegar are all excellent cleaning agents that are both economical and environmentally friendly.
10. Learn and do more!
Participate in water education! Learn more about groundwater and share what you’ve learned.
About Groundwater Arsenic Contamination
Groundwater contamination caused by naturally occurring high quantities of arsenic in deeper layers of groundwater is known as arsenic contamination. It’s a high-profile issue due to the use of deep tube wells for water delivery in the Ganges Delta, which has resulted in widespread arsenic poisoning.
According to a 2007 study, arsenic poisoning of drinking water affects about 137 million people in more than 70 nations. After mass water poisoning in Bangladesh, the problem became a severe health concern. Arsenic pollution of groundwater has been discovered in many nations throughout the world.
The World Health Organization advises reducing arsenic concentrations in water to 10 g/L, but due to the difficulty of removing arsenic from water sources, this is generally an impossible target in many problem locations.
There have been about 20 large occurrences of groundwater arsenic pollution recorded. Four of the largest occurrences took place in Asia: Thailand, Taiwan, and mainland China. In China, the locations of potentially hazardous wells have been mapped.
How to Remove Arsenic from Groundwater
Coprecipitation, adsorption, and ion exchange are three proven treatment strategies for removing arsenic to concentrations below 10 ppb. Choosing an appropriate treatment technology to reduce total arsenic in drinking water necessitates a careful assessment of site-specific variables. Analysis of raw water quality, degree of treatment necessary, the area available for treatment, process simplicity, and treatment/disposal of residual waste generated during the primary treatment process are only a few of these considerations.
- Ion Exchange
Arsenic has a great affinity for iron. Coprecipitation occurs when arsenite is exposed to iron in the presence of an oxidant, resulting in the formation of insoluble arsenate. This method is advantageous since it uses low-cost, reusable backwashed media and produces less waste.
Arsenic removal by coprecipitation can also often be integrated into existing iron and manganese removal systems. In the presence of iron, HMO filters use hydrous manganese oxide media to remove arsenic through coprecipitation. When iron isn’t found naturally in the water, ferric chloride can be used to supplement it. The iron is then oxidized to ferric hydroxide using a pre-oxidant, such as 12.5 per cent sodium hypochlorite.
Simultaneously, any arsenite present is oxidized to arsenate, which is adsorbed as ferric arsenate on the ferric hydroxide carrier floc and then adsorbed on the media. Catalytic activity speeds up the conversion of iron and arsenite, allowing for 100% arsenic removal at high surface loading rates.
The effluent from HMO filters must be backwashed regularly, and it can be sent to a publicly owned treatment plant or a backwash water recovery system. When direct wastewater discharge is not possible, the waste from HMO filtration of arsenic will contain ferric arsenate, a benign salt that can be dewatered and disposed of as a non-hazardous waste subject to passing criteria for the EPA Toxic Characteristic Leaching Procedure and the California Waste Extraction Test.
When molecules of one material adhere to the surface of another, this is known as adsorption. Arsenic molecules adhere to the surface of an iron-based adsorption media when using iron-based adsorption systems for arsenic removal.
Adsorption of arsenic in drinking water, like coprecipitation, is often based on a high affinity between arsenic and iron. A granular ferric oxy-hydroxide media can be used to adsorb both forms of arsenic from drinking water. The media is typically used once to treat pre-chlorinated groundwater containing arsenate in the range of 11 to 40 ppb with neutral pH conditions in this process. At lower pH levels, the media’s arsenic adsorption capability is significantly increased (pH 6 to 6.5).
The reversible exchange of ions adsorbed on a surface with ions in solution that come into contact with the surface is known as ion exchange (IX). Ions are released from the surface of the resin in exchange for other ions in solution in water treatment IX systems. The affinities of the resin for the available ions, as well as the concentrations of the ions in solution, determine the direction of exchange.
Arsenic is found as an anion in groundwater. Ion exchange systems using anion exchange resins and salt brine can be used to extract arsenic. When groundwater contains interfering ions such as silica, sulfate, and phosphate in such high quantities to limit the use of adsorption due to the high frequency of medium replacement, ion exchange may be explored.
When IX is used to remove arsenic, it might result in high arsenic concentrations being released during regeneration. As a result, proper disposal of discharged waste must be taken into account.
Groundwater Contamination – Causes, Effects & Prevention – FAQs
What is the most common source of groundwater contamination?
Effluents (out-flow) from septic tanks, cesspools, and privies are the most common source of groundwater contamination.
What happens when groundwater is contaminated?
Contaminants in groundwater migrate at a slower pace than in groundwater. Contaminants tend to remain concentrated in the form of a plume that flows along the same path as groundwater due to the slow movement. The amount and kind of contamination, its solubility and density, and the velocity of the surrounding groundwater all influence the plume’s size and speed.
This contaminated water can subsequently find its way into surface water, polluting it. When water is pumped from underneath to the surface for various purposes, contaminated water is also pumped, which has negative consequences for us if we use it.
How do you clean up groundwater contamination?
We can clean groundwater contamination by some of the following processes:
- Pump and Treat: This is a typical method for removing dissolved pollutants from groundwater, such as industrial solvents, metals, and fuel oil. Groundwater is recovered and transported to an above-ground treatment facility, where impurities are removed.
- In situ Treatment: This happens when groundwater is treated on-site rather than being extracted from the aquifer. Contaminants can be destroyed, immobilized, or removed using in situ treatment technology.
- Containment: The purpose of this is to prevent groundwater plumes from migrating.
- Monitored Natural Attenuation: This refers to relying on natural processes to achieve remediation goals in a reasonable amount of time.
- Institutional Controls: Non-engineered instruments, such as administrative and legal controls, that reduce the risk of human contamination and/or maintain the integrity of a response action are known as non-engineered instruments.
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